Moulded part for connection to a rim well of a wheel and rim well which is connected to a moulded part

ABSTRACT

There is described a shaped object adapted for being connected with a rim at a point located inside the rim well ( 7 ), having a contact surface ( 2 ) intended to rest on the rim well. It is provided according to the invention that the contact surface ( 2 ) intersects each of a set of mutually parallel first planes ( 3 ) along a curved curve ( 5 ), which is not merely an arc of a circle and whose distance from a second plane ( 6 ), that subdivides the contact surface ( 2 ) and that extends perpendicularly to the first planes ( 3 ) increases with a decreasing growth rate, at least in average, at least on one side of the second plane ( 6 ).

Applicant claims priority from PCT Application number PCT/EP2004/003276filed on 27 Mar. 2004 filed with the European Patent Office and GermanApplication Number 103 14 498.6 filed on 27 Mar. 2003 filed with theGerman Patent and Trademark Office.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a shaped object adapted for beingconnected with a rim at a point located in the rim well, having acontact surface intended to rest on the rim well.

2. Description of Related Art

A shaped object known from EP 0 751 017 B1 has the form of a housingwhich contains a device for measuring the air pressure in a pneumatictire mounted on the rim. The known housing is firmly connected with thebase of a valve by screwing. The valve bore, through which air can bepumped into the tire, is configured for this purpose as a threaded bore,and the housing of the device for measuring the air pressure is providedwith an oblong hole through which a hollow screw can be screwed into thethread of the valve bore. The screw is firmly tightened so that thehousing is fixed on the base of the valve. The valve base is made frommetal for this purpose and its outer shape is that of a sphericalsegment that fits into a recess in the housing of the device formeasuring the tire pressure, which latter is designed as a complementaryspherical cap for this purpose. In order to permit the housing to besupported on the rim well, the housing is provided on its side facingthe rim well with two feet, which are provided with a contact surfacethat gets into contact with the rim well and by means of which thehousing can be placed on the rim well. In order to ensure that the feetwill actually reach the rim well even with rims of different shapes, theoblong hole permits the housing to be fixed on the valve base indifferent orientations relative to the lengthwise axis of the valvebore. This arrangement allows one and the same housing of the device formeasuring the air pressure to be solidly mounted in wheels with rims ofdifferent configurations. However, it is a disadvantage of thatarrangement that for mounting the housing an especially adapted valve isneeded whose valve bore in the valve base is configured as a threadedbore for receiving a special screw with a through bore by means of whichthe housing can be screwed down on the valve base. The speciallydesigned valve and the special screw with passage bore are expensive.

A wheel comprising a device for measuring the tire pressure is alsoknown from DE 196 26 145 A1. In the case of that known wheel it is notthe housing of the device for measuring the air pressure that is screweddown on the valve base, but rather a spring whose free end acts upon thehousing so that the latter is clamped between the free end of the springand the rim of the vehicle wheel in such a way that the housing comes tobe supported, on the one hand, on the base of the rim well and, on theother hand, on two supporting points on the sidewall of the rim well.Thus, the spring urges the housing against both the bottom of the rimwell and the sidewall of the rim well so that the housing is embraced byfour sides, namely by the spring on two sides, by the rim well on oneside and by the sidewall of the rim well on one side. It is adisadvantage of that arrangement that, just as in the case of thearrangement known from DE 0 751 017 B1, an expensive special screw withpassage bore is required for fixing the spring on the valve base. And itis also a disadvantage that differently shaped springs are required forrims of different shapes to urge, and thereby fix, the housing againstthe rim.

It has also been proposed to fix the housing of a device for measuringthe air pressure in pneumatic tires on the rim by means of a restrainingstrap that embraces the rim, lying on the rim well. However, such arestraining strap is connected with the disadvantage that a strap incombination with the necessary tumbuckle is relatively heavy, that forrims of different sizes it has to be individually shortened aftertensioning, and that it may slacken under the influences of temperatureand fatigue.

SUMMARY OF THE INVENTION

Now, it is the object of the present invention to open up a way how thehousing, containing a device for measuring the air pressure in pneumatictires, can be mounted on rims of pneumatic tires of different sizes atrelatively low expense and with the least possible additional mass.

The shaped object according to the invention may be a housing,especially a housing intended to receive a device for measuring the airpressure and/or the temperature in the pneumatic tire. In this case, anegligibly small additional mass, if any, will be required for formingthe contact surfaces. The housing may contain further components,especially a battery, a transmitter, a radio receiver, a roll sensor, acentrifugal sensor, and the like.

Instead of being configured as a housing the shaped object may also takethe form of a carrier or a holder for an object to be mounted on theshaped object, especially a carrier or a holder for the housing of adevice for measuring the air pressure in the pneumatic tire. Theconnection between the shaped object serving as carrier or holder, andthe object received by it may be realized in different ways, accordingto considerations of expediency, for example by a substance connection,by screwing or by a form fit, for example by snapping it onto the shapedobject. Even in case the shaped object is a carrier or a holder or asimilar mounting aid, it can be produced with a minimum of mass, forexample from a plastic material, so that no significant additional massis added to the mass of the object to be mounted on the rim using such acarrier.

The invention provides substantial advantages:

-   -   A single shaped object can fit all imaginable rim types. There        is nothing to be fixed on the valve.    -   Accordingly, there is no need for an expensive special valve,        instead conventional low-cost valves may be used.    -   In configuring the shaped object, or the housing received by the        shaped object, respectively, it is not necessary to consider the        particular design of the valve.    -   The shaped object can be fixed at any desired point of the rim        well, especially at a greater distance from the edge of the rim,        at the lowest point of the rim well. This is favorable in that        it helps prevent imbalances. And in addition, it also reduces        the risk of damage to the shaped object, or to the object        carried by the latter, during mounting of the tire.    -   For mounting purposes, a minimum of mass is required only.    -   The bonding surfaces can be optimized to achieve the highest        possible tensile strength of the bond. The low cost of        manufacture and mounting of the shaped object is unequaled.    -   By varying the size, inclination and/or radius of curvature of        the contact surface, or of sections thereof, it is possible to        optimize the bonding gap geometry for the stresses acting on the        bond with different types of wheels.

The function and advantages of the invention will become more apparentwhen reading the following description of two especially preferredembodiments of the invention.

According to a first embodiment of the invention, the contact surface ofthe shaped object is configured in such a way that each of a set ofmutually parallel first planes intersects the contact surface along acurve of concave shape exhibiting, at least on one side of a secondplane that subdivides the contact surface and extends vertically to thefirst planes, a succession of curved sections whose radius of curvaturedecreases as the distance from the second plane rises. Within eachcurved section, the radius of curvature is preferably constant along thecurve so that the respective curved section of the curve constitutes anarc of a circle. In the case of the described first embodiment, it isintended to give the curved sections a radius of curvature conformingwith, or closely adapted to, the radius of curvature of the rim well ofdifferent rims on which the shaped object is to be mounted. In thiscase, there will then be a matching curved section of the contactsurface, by which the shaped object can precisely apply itself to therim well, for each rim well diameter. There will then exist a constantor substantially constant bonding gap between the contacting section ofthe shaped object and the rim well, which is especially well suited forachieving a strong bond and which easily can be given the necessarylength to achieve the desired tensile strength of the bond.

A contact surface designed in this way adapts itself easily to rims ofdifferent sizes that differ one from the other with respect to thediameter of their rim well. Rims with the smallest rim well diameterapply themselves to one or two sections of the contact surfaceimmediately adjacent the second plane; rims with a bigger rim welldiameter will apply themselves to one or two sections of the contactsurface further away from the second plane, the spacing between thesections and the second plane increasing with the diameter of the rimwell. This allows a reliable substance connection, especially a bondbetween the shaped object and rims of different rim well diameters, itbeing now possible to obtain a sufficiently long bonding zone for allimaginable rim well diameters. This is so because the tensile stressadmissible for a bonding agent depends on the height of the bonding gap,which should not exceed a maximum value depending on the nature of thebonding agent and on the tensile stress to which the bonding layer willbe exposed and which is to be controlled. Supposing a cylindricalsurface, for example a rim well, is to be connected with a flat sectionof a contact surface, the bonding gap starting at the point where theflat contact surface is in direct contact with the rim well willincrease most rapidly for a rim well of the smallest diameter and theleast rapidly for a rim well of the greatest diameter. For a bondingzone formed between a cylindrical rim well and a flat contact surface,the effective bonding zone, ending at the point where the height of thebonding gap reaches a predefined maximum, would be the smallest for thesmallest rim well diameter and the greatest for the greatest rim welldiameter. Compared with that situation, the invention permits theeffective bonding zone to be extended especially for applications wherethe smallest rim well diameter is encountered and an extension of thebonding zone is most important.

Preferably, the sections of different radius of curvature follow eachother directly so that the radius of curvature of the contact surfacechanges abruptly between two adjacent sections, while all in all aconcave shape of the curve is maintained, with the distance of the curvefrom the “second” plane increasing in average over the respective curvedsections. That configuration of the shaped object allows an especiallyshort contact surface to be realized. However, if desirable for otherconsiderations, there is also the possibility, instead of arranging theindividual curved sections corresponding to the different rim welldiameters directly adjacent one to the other, to provide a spacingbetween them in which case the surface areas bridging the spacing neednot be involved in the bonding connection for any of the imaginable rimwell diameters.

Even when sections of a contact surface, which are to be used for thesubstance connection with the rim well, are curved it is still possible,and of advantage, to make additional use of the sections adjoining theone section of the contact surface that is to apply itself against therim well in realizing the bonding connection. This is of particularimportance in cases where the contact surface is to fit a great numberof rim wells of different diameters and where the different curvedsections of the contact surface can be short only. The contact surfacesimmediately adjacent the section of the contact surface that willestablish direct contact, can then be additionally used to form abonding connection with progressively increasing bonding gap. It is ofadvantage in those cases to make the first and the last end sections inthe sequence of sections of the contact surface longer than theintermediate sections because the end sections have a neighboringsection, which may contribute toward increasing the bonding section,only on one of their sides.

The curved sections of the contact surface may be equal or approximatelyequal in length. There is, however, also the possibility to purposefullyselect different lengths in order to optimize the sections for thestresses encountered at the bond with different rims. For example, itmay be of advantage to make the sections longer for smaller diameters ofthe rim well they are to fit so that the section being the closest tothe second plane exhibits the greatest length. Since the abrupt changein radius of curvature encountered between adjacent sections of thecontact surface is the greatest in the neighborhood of the second plane,the contribution which the section neighboring another section, whichfits a given rim, can provide to the effective length of the bonding gapis smaller in the neighborhood of the second plane than in the case ofsections that are further remote from the second plane. In order tocompensate for that disadvantage, it is of advantage if the sectionbeing the closest to the second plane is given the greatest length.

Conveniently, the number of the curved sections on the respective side,especially on both sides of the respective plane, should be suitablyselected for those rim well diameters which the shaped object is to fit.

According to a second embodiment of the configuration of the contactsurface, the latter intersects each of a set of mutually parallel firstplanes along a concave curve which has at least one section, whoseradius of curvature progressively decreases as the distance from thesecond plane rises, on at least one side of the second plane thatsubdivides the contact surface and that extends perpendicularly to thefirst planes. This configuration is achieved by an arrangement where,starting from the configuration according to Claim 3, the number ofcurved sections of a contact surface of predefined length tends towardinfinite. This shows that both embodiments are based on a commoninventive idea.

In the case of the second embodiment, where the contact surface has acontinuously changing radius of curvature, the radius of curvatureshould decrease, as the distance from the second plane rises, over itsfull length at least on one of the two sides of the second plane.Preferably, however, the contact surface of that embodiment should—justas preferred for the first embodiment—also present the claimed radius ofcurvature shape on both sides of the second plane so as to allow asimilar, especially symmetric contact with differently shaped rim wellson both sides of the second plane. This latter aspect is of specialadvantage as it minimizes the occurrence of torques acting on thebonding layer.

Generally, it is possible to give the contact surface a different,especially simpler, configuration on one side of the second plane thanon the other side of the second plane, for example by providing only asingle flat contact surface on one side of the second plane, althoughthis is not preferred, preference being given to a symmetrical design.There is further the possibility to use a mixture of the two embodimentsin configuring the contact surface. The first embodiment, using asequence of arc-shaped sections of the contact surface with differentradius of curvatures is especially suited in cases where the rims, whichthe shaped object is to fit, has a rim well with very narrow dimensionaltolerances. This is however not the rule at present. If greaterdimensional tolerances exist in the rim well, then the second embodimentaccording to Claim 8 will be more suitable and is, therefore, preferred.

Dimensional tolerances are encountered not only in the circumferentialdirection of the rim, but also in its transverse direction. Inparticular, it cannot be assumed that the rim well will always have acylindrical shape. According to a preferred further development of theinvention, it is therefore provided that the contact surface extends inconvex shape along the lines of intersection with third planes thatintersect the curve perpendicularly. A rim well of exactly cylindricalshape throughout would be most suited for achieving an optimum bondingsurface, as the lines of intersection would be straight, not convex, inthis case. Given the fact, however, that in practice one cannot alwaysstart from cylindrical rim wells, and considering that a sufficientlylarge bonding surface is to be achieved with one and the same shapedobject and a plurality of rim well forms, a favorable compromise will beachieved if the contact surface extends in convex shape along the linesof intersection with the third planes that intersect thebefore-mentioned curve at a right angle. The lines of intersection withthe third planes may be constituted by a sequence of straight sectionsforming a polyline in which the angle between successive sectionsincreases from one end of the polyline to the other end of the polyline.However, the lines of intersection may also be curved by sections orcontinuously, with the radius of curvature preferably increasing fromone end to the other end of the line of intersection. Such an asymmetriccontour which—relative to the rim—extends in transverse direction of therim is especially well suited for fixing the shaped object withsufficient reliability also on rims with high dimensional variation andon rims with a non-cylindrical rim well, maybe even on the edge of therim well where the latter starts to transition to a shoulder. Thecontact surface of a shaped object developed in this way resembles theshape of half a saddle.

Suitable materials for the substance connection between the shapedobject and the rim are, above all, bonding agents, especially curablebonding agents, such as two-component epoxy resins and two-component SEpolymers, which allow bonding gaps up to a height of at least 1 mm to berealized. Although cold hardening bonding agents are preferred forreasons of process economy, it is of course also possible to usehot-curing bonding agents. Adhesion of the bonding agents can beimproved by a suitable configuration or pre-treatment of the bondingsurfaces in a way known as such, for example by roughening, etching andstructuring of the bonding surfaces, or by undercuts.

BRIEF DESCRIPTION OF THE FIGURES

A substance connection can also be realized by metallurgical means,however, such a solution would be more expensive compared with a bondingconnection.

Certain embodiments of the invention are shown diagrammatically in thedrawings where the dimensional relations have been exaggerated to makethe essential features of the invention more apparent. Identical parts,or parts that correspond one to the other, are indicated in thedifferent examples by the same reference numerals.

FIG. 1 shows an oblique view of a shaped object with a contact surfacecomprising a sequence of differently curved sections;

FIG. 2 shows a side view of the shaped object of FIG. 1, applied to arim well of big diameter,

FIG. 3 shows a side view of the shaped object of FIG. 1, applied to arim well of small diameter;

FIG. 4 shows a side view of a shaped object, where the radius ofcurvature of the contact surface varies continuously;

FIG. 5 shows a side view of a modification of the shaped objectillustrated in FIG. 4; and

FIGS. 6 to 11 show radial sections of molded parts applied to a rimwell, represented as a radial section relative to the axis of rotationof the rim, representing different contours of the rim well and of thecontact surface of the shaped object.

DETAILED DESCRIPTION OF THE INVENTION

The shaped object 1 illustrated in FIG. 1 has a contact surface 2 ofgenerally concave shape. A set of first planes 3, which extend inparallel one to the other and one of which coincides with the forwardlateral surface 4 of the shaped object, intersects the shaped objectalong curves 5 which comprise a sequence of sections 5 a, 5 b, 5 c thatare differently curved in such a way that starting from section 5 a,which is the nearest to a second plane 6 that intersects the planes 3 ata right angle and that subdivides the contact surface 2, the radius ofcurvature decreases as the distance from the second plane 6 increases sothat the section 5 a has the smallest radius of radius of curvaturewhile the section 5 c has the greatest radius of radius of curvature. Asa result, the contact surface 2, on both sides of the second plane 6,consists of a sequence of differently curved sections 2 a, 2 b and 2 cdirectly following each other. In the illustrated example, each of thesections 2 a, 2 b and 2 c constitutes a section of a cylinder envelope.

The arrangement is mirror-inverted, relative to the second plane 6, sothat the section 2 a of the contact surface extends without a transitionfrom the one side of the second plane 6 to the other side of the secondplane 6 and the other sections 2 b and 2 c follow it toward the outside.The sections 2 b and 5 b, respectively, indicated by the same referencenumerals on different sides of the second plane 6, have the same radiusof curvature and the same center of radius of curvature, the latterlying on the second plane 6. The same applies correspondingly to theremaining sections 5 c and 2 c, respectively, indicated by the samereference numerals.

If a shaped object of the kind illustrated in FIG. 2 is applied to acylindrical rim well 7 of big diameter, then the shaped object 1 canapply itself snugly to the rim well 7 by the outer sections 2 c of thecontact surface 2. When the shaped object 1 is bonded to the rim well 7,a bonding layer of substantially constant layer thickness can form inthe area of section 2 c of the contact surface. Starting at the edge ofthe outer section 2 c, a gap 8 will open in the direction of the secondplane 6 between the rim well 7 and the contact surface 2, which up to amaximum height dmax, which depends on the nature of the bonding agentand on the required tensile strength of the bond, contributes to therequired tensile strength of the bond when filled with bonding agent upto the height dmax of the gap. This zone, reaching to the height dmax ofthe gap, is described herein also as bonding zone 9.

When the shaped object 1 according to FIG. 3 is applied to a rim well 7of smaller diameter, then the inner section 2 a of the contact surfacecan apply itself snugly to the rim well 7 and the bonding zone extends acertain length beyond that contact area on both sides of the section 2 ainto the area of the section 2 b.

In the case of a rim of mean diameter, the shaped object 1 can adaptitself snugly to the rim well 7 by the sections 2 b of its contactsurface 2. In that case, the bonding zone 9 can extend into theneighboring sections 2 a and 2 c, on both sides of each of the sections2 b, until a predefined maximum width dmax of the gap is reached.

What has been illustrated in FIGS. 1 to 3 for three sections ofdifferent radii of radius of curvature can be extended to a largernumber of different radii of radius of curvature, depending on thenumber of different rim well diameters which the shaped object 1 is tofit.

FIG. 4 shows a side view of an embodiment of the shaped object 1 wherethe contact surface 2 exhibits a continuously varying radius ofcurvature, resulting as a borderline case from the first example if thenumber of discrete sections 2 a, 2 b, 2 c of the contact surface isselected to tend toward infinite over the predefined overall length ofthe contact surface 2.

Compared with the embodiment illustrated in FIG. 4, the embodimentillustrated in FIG. 5 is modified in that—just as in the example of FIG.4—the radius of curvature of the curve 5 on the one side of the secondplane 6 decreases continuously as the distance from the second plane 6rises, whereas the contact surface 2 on the other side of the secondplane 6 follows a straight line. This comparison shows that the lengthof the connection zone 9, up to the point where the maximum height dmaxof the gap is reached, is clearly shorter in the area where the contactsurface has straight boundary lines than on the other side of the secondplane 6.

FIGS. 6 to 11 illustrate the adaptation of the contact surface 2 to arim well 7 in a third plane, in which the axis of rotation of the rim islocated, i.e. in a radial plane of the rim. That third plane is theplane of projection in each of FIGS. 6 to 11, while in FIGS. 2 to 5 itextends perpendicularly to the plane of projection. Given the fact thatit is only the shape of the two surfaces of the rim well 7 and of theshaped object 1 facing each other that matter for purposes of thepresent discussion of the existing relationships, both the rim well 7and the shaped object 1 are shown in a very simplified block form only.

FIG. 6 illustrates the case where the rim well 7 has a cylindrical shapein the area in which it is in contact with the shaped object 1. In atransverse direction 10 of the rim well 7, extending in parallel to theaxis of rotation of the rim, a connection zone 9 of constant gap heightcan then be obtained if the contact surface 2 consists—as illustratedfor the previous embodiments—either of cylindrical sections (FIGS. 1 to3) or of flat sections or generally of sections with straight borderlines in the transverse direction 10. Unfortunately, however, thisfrequently is not the case. The rim well 7 often has a conical shape, asillustrated in FIG. 8. In such a case, the effective connection zone 9,up to the gap height dmax, is then more or less reduced, depending onthe cone angle. This is undesirable. In can be counteracted by givingthe conical surface 2 in the transverse direction 10 the configurationof a polyline, instead of the straight boundary line illustrated inFIGS. 6 and 7, with the result that the contour of the contact surface 2becomes more or less convex in the transverse direction 10. The simplestexample of such an arrangement, in which a polyline consists of twostraight sections, is illustrated in FIGS. 8 and 9. It can be seen inthose Figures that although the connection zone 9 is shortened intransverse direction 10 in the case of a rim with an exactly cylindricalrim well 7, this disadvantage is, however, balanced out by the fact thatthe length of the connection zone 9 increases, compared with the caseillustrated in FIG. 8, when a shaped object 1 of that configuration isbonded to a conical rim well 7—see FIG. 9. Bending the contact surface 2off in transverse direction 10 therefore constitutes an advantageouscompromise between the boundary cases illustrated in FIGS. 6 and 7.

The development of the contact surface 2 in transverse direction 10 canbe optimized if the contact surface 2 is not simply bent off, asillustrated in FIGS. 8 and 9, but if instead a polyline is used to giveit a contour, represented by the line of intersection 11 with the thirdplane 12, of the kind illustrated in FIGS. 10 and 11 where the radius ofcurvature increases in average from one end of the shaped object 1 (theleft edge in FIG. 10) toward the opposite edge of the shaped object 1.Instead of a polyline, the line of intersection 11 may also be given acontinuous radius of curvature, approximated to it in transversedirection 10. The contour of the contact surface 2 then resembles thatof half a saddle. It is the optimum achievable if one and the sameshaped object 1 is to be used for a large number of different rim wells.

LIST OF REFERENCE NUMERALS

-   -   1. Shaped Object    -   2. Contact surface    -   2 a. Section    -   2 b. Section    -   2 c. Section    -   3. First planes    -   4. Lateral surface    -   5. Curve    -   5 a. Section    -   5 b′ Section    -   5 c. Section    -   6. Plane    -   7. Rim well    -   8. Gap    -   9. Connection zone    -   10. Transverse direction    -   11. Polyline    -   12. Third plane

1. A shaped object, in combination with a rim of a wheel, said shapedobject located inside the rim's well, having a contact surface intendedto rest on the rim well, wherein the contact surface intersects each, ofa set of mutually parallel first planes along a curved surface which isgenerally elliptical, said curved surface having a radius of curvaturewhich has a curvature growth rate, wherein the growth rate decreases toa limit value as the distance of the curve from a second plane rises,and then remains constant as the distance continues to rise.
 2. Theshaped object as defined in claim 1, wherein the shaped object isattached to the rim well by a bonding agent between the contact surfaceand the rim well.
 3. The shaped object as defined in claim 1, wherein itis a carrier or a holder for a housing.
 4. The shaped object as definedin claim 1, wherein it is a housing.
 5. The shaped object as defined inclaim 4, wherein the housing contains a device for measuring thepressure and/or the temperature in a pneumatic tire which is mounted onthe rim.
 6. A rim with a shaped object as defined in claim 1, which hasits contact surface connected with the rim at a point inside the rimwell by a substance connection.
 7. A rim as defined in claim 6, whereinthe shaped object is bonded to the rim well.
 8. A Shaped Object adaptedfor being connected with a rim at a point located inside the rim well,as according to claim 1, wherein the Shaped Object is attached to therim well by a bonding agent between the contact surface and the rimwell.
 9. A Shaped Object as defined in claim 8, wherein said bondingagent is a durable bonding agent.